July 28, 2015
Data Locality in Hadoop Data Locality in Hadoop refers to the “proximity” of the data with respect to the Mapper tasks working on the data. Why […]
July 19, 2015
Hadoop Modes Hadoop cluster is made up of several key process and each process is designed to do a specific task. Here are the key daemons […]
July 14, 2015
JobTracker and TaskTracker JobTracker and TaskTracker are 2 essential process involved in MapReduce execution in MRv1 (or Hadoop version 1). Both processes are now deprecated in […]
July 12, 2015
NameNode and DataNode In this post let’s talk about the 2 important types of nodes and it’s functions in your Hadoop cluster – NameNode and DataNode. […]
July 3, 2015
How to change default replication factor? What Is Replication Factor? Replication factor dictates how many copies of a block should be kept in your cluster. […]
June 25, 2015
How to change default block size in HDFS? In this post we are going to see how to upload a file to HDFS overriding the default […]
June 25, 2015
“Working With HDFS” chapter in our Hadoop Starter Kit course covers the details on working with HDFS. In that chapter we looked at how to copy, […]
June 20, 2015
What is Hadoop? – A beginner’s tutorial to understand Big Data problem and Hadoop In this Post we looked at What is Big Data. To learn […]
June 19, 2015
What is Big Data? – A beginner’s tutorial In this blog post, we are going to see the following What is Big Data? Examples of Big […]
June 5, 2015
One of my close friends recently joined Microsoft in Seattle in their highly acclaimed data analysis team. I asked him what was his first assignment. He […]
October 22, 2014
3 years ago only a small number of companies were using Hadoop. Now Hadoop technology has grown leaps and bounds so as its user base. Companies […]
September 24, 2014
This post will explain how can you approach the above question when asked in an interview. This is an open ended interview question and the interviewer […]
June 18, 2014
This post explains the class relationship when we use ToolRunner to run a MapReduce job. It is not really complicated but we use the below pictorial […]
May 11, 2014
This post explains how to unit test a MapReduce program using MRUnit. Apache MRUnit ™ is a Java library that helps developers unit test Apache Hadoop map […]
April 19, 2014
What is Million Song Dataset ? The Million Song Dataset is a freely-available collection of audio features and metadata for a million contemporary popular music tracks. The […]
April 4, 2014
If you are new to Hadoop, you are probably tired of WordCount and want to get hands on with some real use cases. Page ranking is an […]
March 3, 2014
Executions in Hadoop use the underlying logged in username to figure out the permissions in the cluster. When running jobs or working with HDFS, the user […]
February 17, 2014
There could be several reasons when you see “could only be replicated to 0 nodes” message in your exception when you are trying to write something […]
February 8, 2014
This post explains how to write a Oozie MapReduce action with Multiple Inputs and how each Inputs are configured to use different InputFormats and Mappers Lets […]
February 2, 2014
This post explains the fix when you see the below error when starting Datanode. 2013-12-14 23:39:09,354 ERROR org.apache.hadoop.hdfs.server.datanode.DataNode: java.io.IOException: Incompatible namespaceIDs in /tmp/hadoop-hadoop-user/dfs/data: namenode namespaceID […]
